Anchorage, Alaska (CNN)If braving 100 miles of snow, ice and the freezing winter temperatures those elements imply, through the Alaskan bush, sounds like a good time to you, you may be extra thrilled by the option to race those dozens of miles of wilderness on foot, skis or bike.
This is the Susitna 100, a unique race that has challenged its participants to brave the elements and their own limits for the past 22 years.
The race is open to everyone but is not exactly for everyone. You have to be very fit, particularly if you ski or run this ultramarathon. You have to be equipped for the mental highs and lows that come with all ultras.
And you must be nimbly prepared for varying race conditions and potential problems that are unlike most every race of its length. And finally, you must be brave, as the dangers of injury, frostbite and hypothermia are rare but real.
Choose your own adventure
These kinds of winter endurance or wilderness races exist in a few other places on the globe, but they are a niche sport among traditional ultramarathons. The ones where you can decide your own mode of transportation are so rare, they don't have a special name. (Though I say we all try to get "Iditirace" to stick. "I did a race!")
For the Susitna 100, most racers choose to embark upon this the snowy "century" on a specialized fat-tire bike built for such conditions. Being on a bike means your beautiful but chilling purgatory can last from eight to 40 hours. Cross-country skiers need to be extremely fit to continuously push through the sometimes powdery, sometimes icy terrain in 12 to 48 hours.
But it's the ultramarathoners who run nearly continuously for 18 to 48 hours, who display the greatest level of endurance in terms of managing the weather and their own physical and mental fortitude. Before it's over, some runners will have experienced three sunrises, two nights of running, perhaps a few harmless hallucinations, serious blisters and numbing sleep deprivation.
The runners also do this while pulling a sled with at least 15 pounds of required emergency gear that will keep them alive if they get lost or injured and need to stop and wait to be found. First-timers tend to bring too much gear. "You carry your insecurities with you," said Kim Kittredge, the Susitna 100 race director.
Conditions vary so much from year to year that athletes are allowed to change their mode of transportation up to the last moment. Some may choose to drop out if the conditions are poor for skiing or biking, but others who were training for those categories have decided to run in the days and hours before previous races.
If there's too little snow, skiing becomes difficult, and the ice can spill and injure cyclists and tear up runners' sleds. Too much snow, and bikers will end up exhaustingly pushing their bikes through much of it.
The nemesis of all the racers is called overflow, a phenomenon in which water gets trapped on top of otherwise-frozen rivers and ponds, a hazard that can soak a racer and cause problems ranging from blisters to frostbite. Snow on top of overflow can become a thigh-high slushy morass.
The ideal "Goldilocks" conditions are "a hard-packed trail with little new snow and temperatures in the teens," explained Kittredge. Knowing what to expect "makes it easier to pack your food and your gear, and (those conditions mean) less resistance on the trail."
Call of the wild
On the morning of the race in 2017, about 150 athletes began to assemble before dawn at Happy Trails Kennels, about a 60-mile drive west of Anchorage in the shadow of the Chugach Mountains.
The racers, 90% of whom are from Alaska, were in good spirits and chatty, as most know each other at least from previous races. They are also cold, on purpose. They know they will soon warm up, and this year was not particularly chilly, which meant fewer layers and softer snow to sweat through.
The kennel is owned by Martin Buser, a former winner of the fabled Iditarod dog sled race. Winning that particularly grueling race of 1049 miles is the Alaskan equivalent of winning the US Open, a Heisman Trophy or the Triple Crown. Buser won four times. So the pre-race excitement buzzed a bit more when the mushing celebrity showed up to say hello and wish people good luck in his friendly, low-key manner.
At dawn, an announcer called the racers to the starting line with bikes in front and counted down to the start. In a noisy burst, the racers -- on foot, tire or ski -- all took off at the same time. They headed down an icy road that turns into a trail that becomes wilderness within the first mile. Soon after that, the pack starts to thin out as bikers pull out ahead and athletes get into their own rhythms.
One runner, Brandon Wood, 35, explained how long hours of running alone led to his mind playing tricks on him. On the second day, the terrain is a wide-open swampy area that gives little indication you're making much progress. "There were quite a few times where I thought I'd see someone off in the distance, and every single time it was a tree."
About 10% of the racers don't finish, usually voluntarily. The reason is rarely slowness, because the time windows are quite generous. For some, it's about the race conditions; others get hurt or are feeling ill. Some just find it too demanding, because they didn't train properly or didn't have the right gear.
There is no cap on the number of racers -- Alaska has the room for everyone -- and until about 2010, it was mainly around 70 or 80 runners and skiers. But the availability and affordability of fat tire bikes has roughly doubled the total just in the past five years. This year, 101 bikers, 31 runners and 15 skiers registered.
The finish line is a rather quiet affair. Some racers may have a friend or loved one there to cheer them on, but finish times are too spread out and the temperature is too cold to have groups of people standing around waiting for hours.
There is no prize money for the category winners, just bragging rights. All the finishers get a T-shirt and belt buckle and an enormous sense of accomplishment. Then they go off to find a warm place to finally rest.
But it's not all so isolated. Most racers stuck around for the Monday night party at the Tap Root bar in Anchorage to celebrate, brag, complain and bond over what they accomplished and how they are probably crazy enough to try it again next year.
Human vs. human vs. nature
To prepare for a race like the Susitna 100 is not that unlike most ultra races. Over the previous months, you need to work your way to greater distances using interval training. Mileage schedules are easily found online.
One important difference is the conditions. Running 100 miles is much easier (if the first half of the sentence doesn't already sound ridiculous) on solid ground, a phenomenon familiar to anyone who has run on sand. Ideally, training includes some distances in cold temperatures and on snow.
Another key difference for runners: That minimum of 15 pounds of required gear behind them in a sled. The mandatory gear includes a sleeping bag rated minus-20 degrees Fahrenheit, a bivy sack or tent, sleeping pad, and a day's worth of food. But runners need to try out the sled and some even fashion their own and pull something else, like a tire, in training.
Skiers can choose to either skate ski or classic parallel, applying kick wax for speed. They can pull a sled too, but most tend to prefer backpacks.
Probably the biggest factor of success or failure for a winter wilderness race is what racers call "moisture management." Just as there are optimal course conditions, there are optimal self-temperature ones, as well.
"There's a fine line you have to walk," explained Wood, who finished second among runners this year. "You need enough clothes to be warm enough but not too much that you sweat through all your clothes and risk hypothermia, especially if you slow down or get injured -- then, suddenly, you're out there in soaking wet clothes."
As far as clothing, layers of normal outdoor apparel are what's mainly called for: a midweight shirt, fleece, a windbreaking layer, puffy coat, tights, long johns. Runners prefer Gortex shoes and gators to keep snow out of them. Some bring overboots just for water crossings and wisely bring extra socks and a pair of shoes in case they get wet (and they will).
Racers each have a technique for keeping water from freezing when the temperature dips that low, such as routing a CamelBak hose under one's arm.
The physical benefits of biking, running and cross-country skiing are all well known. Although they target different muscles, they are excellent cardio activities, and depending on the wintry course conditions, the workout is only amplified. Just remember, the more carbs you burn, the more you need to replace in that zero-sum game of energy consumption.
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And adventure racing, especially in sub-zero temperatures, also carries risks. Hypothermia (a sudden drop in body temperature) is life-threatening, and frostbite (freezing of the skin) can leave lasting scars. Blisters on feet are common for the runners and skiers. And this year, someone had trench foot (infection due to prolonged cold wetness). Broken bones are not uncommon in the history of the Susitna 100, either.
There have also been racers who have gotten lost, even though the trail is very well-marked. It happened to one racer this year. But with checkpoint times recorded, the coordinators have a sense of when a racer is taking too long, and help is quickly mobilized. One year, the organizers had to evacuate 20 racers due to a big snowfall. And when racers find themselves injured or lost in the dark in unforgiving conditions of the wild, that's when their 20-below sleeping bags can possibly save their lives.
But those instances are rare for the race. For most, their story has a happy, if exhausting, ending. The feeling of accomplishment after an endurance race that uniquely challenges the mind and body is what keeps racers coming back for more.
"If you put yourself up to the challenge," Wood said, "you'll be amazed by what you can accomplish."